I. Field
The present disclosure relates generally to wireless communications and more specifically to transmitting buffer status reports.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), etc.
Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more access points (e.g., base stations, femtocells, picocells, relay nodes, and/or the like) via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from access points to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to access points. Further, communications between mobile devices and access points may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or access points with other access points) in peer-to-peer wireless network configurations.
In fully scheduled systems, such as LTE, access points can provide uplink resources to mobile devices upon receiving indication that such resources are required to transmit data to the access point. In one example, mobile devices can provide buffer status reports (BSR) to the access points in certain scenarios to trigger downlink resource assignment from the access point. The BSRs, for example, can additionally indicate a size of data in the buffer, which the access point can use to determine a resource allocation size for the mobile device.
Mobile devices currently transmit BSRs in three scenarios: when data arrives in the uplink transmission buffer at the mobile device that belongs to a radio bearer of higher priority than data currently in the buffer, when uplink shared channel resources are allocated and a number of padding bits is larger than the BSR size, and when the mobile device arrives at a new cell. The first scenario additionally triggers a scheduling request to the access point to receive an uplink grant for transmitting the BSR, whereas in the latter two scenarios, the uplink grant has been received and a BSR can be transmitted thereover.